Base-line telemeter.



0. VON HOPE. BASE LINE TELEMETER, APPLICATION FILED Novv Patented May 6, 1913 mamas;

2529 W /M/J CHRXSTEAN VON HOFE, Oil WILHEBSDQRF, NEAR BERLIN, GERMANY, ASSIGNOB TO THE FIRM F OPTISCHE ANSTALT G. IQ'EAB BERLIN, GERMANY.

KP. GOEJRZ AKTXENGLE$ELLSCHAFR OF FBIEDENAU,

BASE-LINE TELEMETER.

Application filed November l, 1911.

Specification of Letters iatent.

Patentcdlllay 6,1913. Serial No. 658,475.

1 b all whom it may concern Be it known that l. inus'run' vox Horn, u citizen of the German Empire and resident of Wilmersdorf, near Berlin, Germany, have invented certain new and useful linpro 'enients in liaise-Line 'lelemeters, of which the following-is a specification.

This invention relates to base line telem- .eters provided with a compound ocular prism device for uniting the images of distmu' objects produced from the ends of the base line of the instrument having a reliectiue' layer in a contacting surf of the ular prism device.

llhire particularly the invention relates to base line telemcle-rs ofihe said hind where the edge of the reflecting layer provided in the contact surface of the ocular prism device is arranged in a conuuon focal plane of the two obj cctives parallel to the plane of the measuring triangle and at right angles to the axis of the. rays which penetrate that part of the contact surface of the ocular prism device which is not. provided with the said reflecting layer. r

The invention consists in such a construction of the ocular prism device of instruments referred to that a direction of view for the observer is obtuinedlwhich is incl incd to the plane of the triangle of observation, this allowing in many cases a more comfortable observing position than a direction of observation parallel to the plane of the measuring triangle Th1 ee embodiments of the new ocular prism device are represented on theaccomnanving drawings.

Figure 1 shows a plan of the new ocular prism device the principal optical elements of the tcleincler being at. the same time indicated diagrammatically by dotted lines. Fig. 2 shows a lateral view of the ocular prism device of Fig. 1 and thesaid principal optical elements of the telemeter. Fi s. 3 and 4 and 5 and 6 respectively show two modified forms of i the new ocular prism device.

Referring more particularly to Figs. 1 and 2 of the drawings the two objectives of the telemeter are designated 1. 2 and the ocular 3. The pcnta prisms arranged in front of the objectives l. 2 are indicated at iand The ocular prism device-consists of the compound oeular prism proper coniace of prisms posed of the prisms (3, 7 and of two lgfleviating prisms l3, 14 adapted to receiv the rays coming: from the objectives and throwme' same to the ocular prism proper. The compound ocular prism proper is provided with two reflecting; surfaces 8, l) converging toward each other. A reflecting layer 10 is provided in the contacting surface of the prisms t3. 7, said reflecting layer having: an cdge'l-l forming the horizontal line of division in the image field of the instrument. 12 designates the exit surface of the conipound-ocular prism which is arranged inclined to the plane of the measuring triangle and at right angles to the axis of the ocular. The deviating prisms 13, 14 are provided with (EI'OSSlIlg reflecting: surfaces lfnlll.

The operation of the device is as follows: Rays coming from an object, the distance of which to be measured, are reflected bv the surfaces of the penta prisms 4, 5 and thrown into the objectives 1. whereafter they impinge on the surfaces 15, 16 ofthe deviating prisms 1?). 14. The reflecting surface 'lfiof-the prisnrlii reflects the rays to thc surface S of prism (3 where they are reflected 511 -a direction perpendicularlv to the surface l2 so that these l'avs are thrown direetlv into the ocular 3. The rays coming from the objective 1 impinge on the surface to which rcllccts them to the surface 9 where thev receive a further reflection whereby they are thrown on the reflecting layer 10. The reflecting layer 10 reflects the rays in a direction pcrpendicularlv to the exit surface 12 into the ocular. It ap- DktllS from the foregoing description that the edge ll of the reflecting layer 10 forms a line of division in the field of View as above stated which is positioned lmriz-zoutallv and appears sharp in its whole length according to its being positioned in a common focal plane of the objectives. The rays missingthrough the objective 2 enter the ocular after havingrlwcu four times reflected namely twice by surfaces of the penta prism once by the surface and once by the surface. 8. The image produced by the rays passing; through objective 2 therefore apiears upright and rightsidcd. The rays coming from objective 1. are reflected five times namely twice by surfaces of penta prism 4-, once by reflecting surface 16 of prism 14, once by reflecting surface 9 of prism 7 and once by reflecting layer it). The image of the objects produced by ob jective 1. therefore appears inverted so that the base line telemeter with the prism ocular device of Fig". i operates as a so-called in rcrt. base line telemcter. it a 'alled coincidence telen'ieter it would be necessary to proride an even numhcr of reflect ions also for the rays passing through objective '1.

The ocular prism device i'lustratcd in Figs. 23 and 4' is distinguished from the dericc of l igg s. l and :2 by combiningprisms Ll?) and it witlrprisms ti and 7 respectively to prisms l8 and 19 and by providing the exit surface of the rays coming from oh jectirc 1 on a special prism 20 cemented together with prism 19. Said exit surface of prism 20 is in this instance designated 21 and the crossing reflecting surfaces of prisms 18, 19, are designated 22, 23; the retlectin layer in the Ctlllttltfl" surface of prisms 18, 19 is designated 2i.

In the embodiment of the ocular prism de vice illustrated in Figs. 5 and 6 the inclinations of the reflecting surfaces of the two prisms forming the ocular prism toward the reflecting layer in their contact surface are so calculated that the exit surface for the rays coincides with one reflecting surface of the ocular prism so that a special exit surface is dispensed with. The two elements of the compound ocular prism are dos-V ignatcd :55. 26; same are provided each with a reflecting surface 2?, 28, these two surfaces In order to make" prism Z in Fig. 2. 31 is the reflecting layer in the contact surface of prisms $25, #243 and its limiting edge.

What It claim is:

in a base line tclcmeter in combination with two objectives and one ocular an ocular prism dc \icc comprising two prisms contacting with each other in a surface crossing the field of view of the ocular, a reflecting layel prorided in a part of said contact surface and having a limiting edge arranged paral lel to the plane of the mcasm'ing triangle and at right angles to the axis of the raysuhich penetrate that part of said contactsuri'ace which is not provided with the rotiecting layer, the prisms of the ocular prism dcricc contacting with said reflecting layer being provided with reflecting surfaces eonvcrg'ing toward each other and including the reflecting layer within the angular space formed by them, reflecting means adapted to throw the rays coming from said two objectires on said converging reflecting surfaces of the ocular prism device and an exit.- surface provided at the ocular prism device said exit surface crossing the path of the rays coming from said two converging prism surfaces and advancing toward the ocular and arranged at right angles both to the rays reflected from one of said two converging surfaces of the ocular prism and to the rays reflected from the reflecting layer after rctlection from the second of said t'WO com'crgiug prism surfaces.

in testimony whereof I have signed-this specification in the presence of two subrise 

